Run your favorite 31.8mm clamping diameter handlebar on a bike with Knock Block with the Rhythm Comp 31.8. It adds Knock Block compatibility to a durable stem with multiple lengths to let you fine-tune the fit to your ride.
Get 31.8mm handlebar compatibility with your Knock Block system;Also compatible with standard headsets and spacers;Knock Block system protects frame from impacts by fork and handlebars by eliminating over-rotation of bars;Available in a wide range of sizes for today's mountain rider;See Service Parts for other Knock Block parts;

Trim some weight and add some style to your ride with Bontrager's RXL Stem. Made from forged 7050-T6 aluminum, this stem is exceptionally light and strong. In fact, it's equally suited to the sharp impacts of mountain biking as it is to the long-mile rigors of the road. And, its shot-peened finish offers exceptional strength while the 4-bolt faceplate makes installation easy, and the opposed-bolt steerer clamp is carbon friendly.

Downhillers rejoice! Bontrager has a stem for you. Maintain confident control on screaming runs down the gnarliest lines with the durable and strong Rhythm Pro Direct Mount Stem.
Made from strong and lightweight 6061 aluminum, this stem features a hefty 4-bolt attachment to the fork, and a 4-bolt, dual-band clamp for a confident interface with the bars.
Key features:
- Constructed of 7050 alloy
- 4-bolt direct mount for dual crown forks
- 4-bolt dual band clamp securely holds handlebar
- Uses M6 corrosion-resistant steel bolts with 8Nm torque spec
- Safe for use with alloy or carbon handlebars

The Madone is built as a seamlessly integrated machine designed to do one thing: go fast. Trek's Madone Integrated Bar/Stem is an important part of that integration. Available in a variety or widths and reaches so you can dial in your superbike specifically for you.
- Compatible with model year 2016/17 Madone
- Variable radius, compact flare (VR-CF) shape offers wrist clearance in the drops
- 100% OCLV carbon fiber construction
- Seamless accessory integration with Blendr
- Blendr accessory bases and mounts sold separately

Cannondale's OPI Stem is the ultimate lightweight upgrade for your Lefty Fork. Its 2-piece threaded design is made of durable, lightweight 2024 aluminum. Available in a wide range of lengths and rises, dialing in your perfect fit is a breeze.

Electra's Cruiser Aluminum Stem is a stable, solid replacement for your original equipment. Designed to work with a 1-inch headset, the Cruiser Stem is made from no-frills aluminum that keeps off the weight while maintaining strength where you need it.

Profile's Aris OS stem is a no-nonsense stem made from 6061-aluminum that's been shot peened and anodized for strength and durability. The 4-bolt faceplate is stiff, ultra tough and makes handlebar changes a breeze. And, the opposing-bolt steerer clamp is safe and secure.

When stiffness and weight are the top on your list, you want Ritchey's Carbon Matrix C-260 Stem. The C-260 is 3D forged from 7050 aluminum with a carbon exoskeleton to enhance rigidity. Even the steel M4 bolts shave a few grams with no sacrifice in strength. This revolutionary design starts with a bar clamp that wraps a full 260-degrees around the handlebar to distribute clamping stress evenly through the handlebar, faceplate, hardware and stem body. The steer tube clamp uses three bolts and a curved slot to reduce clamp stress on the steer tube, so you can run carbon bars and a carbon steerer with no problem.

Sunlite's Adjustable Stem adjusts from 0 to +60 degrees so that you can place your handlebars wherever they are most comfortable. It boasts light and durable aluminum construction with steel bolts. It fits on 1- and 1 1/8-inch forks and accepts 25.4mm- and 31.8mm-diameter handlebars too, with included shims. Plus, its 2-bolt clamp makes changing bars easy and holds fast.

The Elite X4 Mountain Stem is instantly recognizable because of Thomson's legendary style, and with strength to spare, this stem is more than just a pretty face. Made from a solid, one-piece block of 7000-series aluminum, the X4 combines exceptional strength with light weight for durable, solid steering control to tame the toughest trails. It has a four-bolt clamp design and reversible graphics, so your X4 looks great whichever way you run it.